1. Field of the Invention
The present invention relates to a solid-state laser, and more particularly, to a DPSS (Diode Pumped Solid-State) laser.
2. Discussion of the Related Art
In general, a DPSS laser has high efficiency and a large output-power in a relatively small size compared to a regular laser. Accordingly, there is an increasing trend of applying the DPSS laser to an industrial technology such as marking or cutting. Furthermore, recently, the DPSS laser is in a process of development as a display light source owing to characteristics of a small size, high efficiency, and the large output.
The DPSS laser is divided into an end pumping type and a side pumping type. Hereinafter, the DPSS laser will be described in more detail referring to appended drawings. FIG. 1 is a drawing of an end pumping type of DPSS laser. As illustrated in FIG. 1, when a pumping light radiated from a laser diode (LD) 110 is incident upon a laser material 140 after passing through a focusing lens 120, the DPSS laser forms the pumping light in beam mode at the laser material 140 so as to output a lasing light through an output coupler 150.
In this case, PR (partial reflection) coating 130 for the lasing wavelength is formed on a front surface of the laser material 140 for transmitting only a part of the radiated pumping light.
The end pumping type of DPSS laser has efficiency and an advantage in forming the radiated light in beam mode because the lasing area of the laser material 140 overlapping the radiating area of the laser light is large.
However, the end pumping type of DPSS laser has a predetermined limitation in a large output of the laser power owing to a heat lens phenomenon.
FIG. 2 illustrates a drawing showing a side pumping type DPSS laser in accordance with a related art. As illustrated in the drawing, when the pumping light radiated to the two laser diodes 210_A and 210_B provided at both sides of the laser material 240 is transmitted through the laser material 240, the pumping light is formed in the beam mode at the laser material 240 so as to output the lasing light through the output coupler 250 in the DPSS laser.
In this case, only the part of the PR (partial reflection) coating for a lasing wavelength is formed on a front surface of the laser material 240. On a rear surface of the laser material 240, the lasing light proceeds in one direction because HR (high reflection) coating 260 for the pumping wavelength is formed and totally reflected.
Although the DPSS laser of the side pumping type is advantageous for a large output owing to a prolonged lasing area, efficiency of the pumping light is lowered and there is a disadvantageous problem in forming the beam mode.
If the laser is employed as a display light source, a condition for the large output of the laser power, efficiency of the pumping light, and a small size production needs to be satisfied.
Therefore, a development of the laser is needed for enabling lasing with a large output and improving the efficiency of the pumping light by elongating a length of the laser material.